Get json and store value to other page in android

MainActivity.java

import android.content.Intent;
import android.os.Bundle;
import android.os.Looper;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;
import org.json.JSONException;
import org.json.JSONObject;

import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity {

    private EditText txt_username, txt_password;
    private Button btn_login;
    private String uriAPI = "http://study.ar-leung.net/android/index.php";
    Intent intent = new Intent();
    Bundle bundle = new Bundle();

    @Override
    public void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        txt_username = (EditText) findViewById(R.id.txt_username);
        txt_password = (EditText) findViewById(R.id.txt_password);
        btn_login = (Button) findViewById(R.id.btn_login);
        btn_login.setOnClickListener(sendlistener);
    }

    public View.OnClickListener sendlistener = new View.OnClickListener(){
        public void onClick(View v){

            if (v == btn_login){

                if (txt_username != null && txt_password != null){
                    Thread thread = new Thread(new Runnable() { public void run() {
                        try {
                            JSONObject obj = sendPostDataToInternet();
                            System.out.println(obj.getString("username"));
                            System.out.println(obj.getString("password"));

                            if(obj.getString("status").equals("success")) {
                                // Bundle - Store date to other activity
                                bundle.putString("username", obj.getString("username"));
                                bundle.putString("password", obj.getString("password"));
                                intent.putExtras(bundle);
                                intent.setClass(MainActivity.this, Transaction.class);
                                startActivity(intent);
                                MainActivity.this.finish();
                             }else{
                                Looper.prepare();
                                Toast.makeText(MainActivity.this, "Login Fail", Toast.LENGTH_SHORT).show();
                                Looper.loop();
                             }
                        } catch (JSONException e) {
                            e.printStackTrace();
                        }
                    }});
                    thread.start();
                }
            }
        }
    };

    private JSONObject sendPostDataToInternet(){
        HttpPost httpRequest = new HttpPost(uriAPI);
        List params = new ArrayList();
        params.add(new BasicNameValuePair("username", txt_username.getText().toString()));
        params.add(new BasicNameValuePair("password", txt_password.getText().toString()));
        try{
            httpRequest.setEntity(new UrlEncodedFormEntity(params, HTTP.UTF_8));
            HttpResponse httpResponse = new DefaultHttpClient().execute(httpRequest);

            if (httpResponse.getStatusLine().getStatusCode() == 200){
                // Get php string 
                String strResult = EntityUtils.toString(httpResponse.getEntity());
                Log.d("JSON", strResult);
                // String to JSON Object
                JSONObject obj = new JSONObject(strResult);
                return obj;
            } else{
                Log.d("error", "no message");
            }
        } catch (ClientProtocolException e){
            Log.d("@@", e.toString());
        } catch (IOException e){
            Log.d("@@", e.toString());
        } catch (Exception e){
            Log.d("@@", e.toString());
        }
        return null;
    }
}

Transaction.java

import android.content.Intent;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;
import android.widget.Button;

public class Transaction extends AppCompatActivity {

    private Button btn_back;
    Intent intent = new Intent();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_transaction);
        Bundle bundle = getIntent().getExtras();

        // Extract the data
        String username = bundle.getString("username");
        String password = bundle.getString("password");
        Log.d("username", username);
        Log.d("pasword", password);

        btn_back = (Button) findViewById(R.id.btn_back);
        btn_back.setOnClickListener(sendlistener);
    }
    public View.OnClickListener sendlistener = new View.OnClickListener(){
        public void onClick(View v) {
            intent.setClass(Transaction.this, MainActivity.class);
            startActivity(intent);
            Transaction.this.finish();
        }
    };
}

AndoridManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.leung.lbms">
<uses-permission android:name="android.permission.INTERNET"/>
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<application
    android:allowBackup="true"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:roundIcon="@mipmap/ic_launcher_round"
    android:supportsRtl="true"
    android:theme="@style/AppTheme">
    <activity android:name=".MainActivity">
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <activity android:name=".Transaction"></activity>
</application>

</manifest>

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"

    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.leung.lbms.MainActivity"
    tools:layout_editor_absoluteY="81dp">

    <TextView
        android:id="@+id/label_username"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        android:text="Username"
        android:textSize="24sp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <EditText
        android:id="@+id/txt_username"
        android:layout_width="204dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="16dp"
        android:layout_marginTop="16dp"
        android:ems="10"
        android:inputType="textPersonName"
        android:text="leung"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/label_password"
        android:layout_width="150dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="16dp"
        android:layout_marginTop="32dp"
        android:text="Password"
        android:textSize="24sp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/label_username" />

    <EditText
        android:id="@+id/txt_password"
        android:layout_width="206dp"
        android:layout_height="wrap_content"
        android:layout_marginEnd="8dp"
        android:layout_marginRight="16dp"
        android:layout_marginTop="16dp"
        android:ems="10"
        android:inputType="textPassword"
        android:text="password"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/label_username" />

    <Button
        android:id="@+id/btn_login"
        android:layout_width="258dp"
        android:layout_height="44dp"
        android:layout_marginEnd="16dp"
        android:layout_marginStart="16dp"
        android:layout_marginTop="33dp"
        android:text="Login"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/txt_password" />

</android.support.constraint.ConstraintLayout>

activity_transaction.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.leung.lbms.Transaction">

    <Button
        android:id="@+id/btn_back"
        android:layout_width="155dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="112dp"
        android:layout_marginTop="76dp"
        android:text="Back"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <android.support.constraint.Guideline
        android:id="@+id/guideline"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        app:layout_constraintGuide_begin="20dp" />
</android.support.constraint.ConstraintLayout>

index.php

<?php
	header("Content-type: application/json; charset=utf-8");
	
	if($_POST){
		$str = '{"username":"'.$_POST['username'].'","password":"'.$_POST['password'];
		if($_POST['username'] == "leung" && $_POST['password'] == "password"){
			$str .= '","status":"success"}';
		}else{
			$str .= '","status":"fail"}';
		}
		echo $str;
	}
?>